William w



June 9,' 1925. 1,541,233 l W. w. MCMAHAN @reiterated June 9, 1925.

n s'rass lWILl'iIlJllI W. MCMAHAN, 01E' DETROIT, MICHIGAN, SSIGNOR TO.MORGAN & WRIGHT, A CGRIPGRATION OF MICHIGAN. l I.

FREPARATION OF LAB/IPBLACK FOR USE IN COMFQUNDING RUBBER.

Application filed November 3, 1916. Serial No. 129,29.

To all li ello/1L it may concern.'

Be it known that l, TVILLIAW `W. Mc- MAHAN, a citizen of the UnitedStates, residinn7 at ietroit, county of Wayne, State ot' li'iichigran,have invented certain new and useful improvements in the Preparation ofiiainpblaek i`or ilsein Compounding ltubber. of which the ollowingnr isa full, clear, and exact description. s

'.i` his invention relates to the preparation of larnpblack for use incompounding rubber, and has for an object to prevent dispersion of thelalnpblack into the' atmosphere during the millingr operation.

Lampblaclt. while being;r compounded with rubber on mill rolls,permeates the atmos-1 phere and smudges the white and other coloredrubber stocks which are being milled inthe same room. ln order to remedythis condition, the present invention provides a process for changingthe physical state of the lampblack from a loose easily dispersablepowder, to a compactly pressed cake or uniss in which the particles arebound together.l b v molecular cohesion. In this condition the. lampblack is capable of beingrr mille-1l with the rubber without theannoying dispersion hitherto encountered.

Apparatus for carryinpT out the invention is shown in the accompanyingdrawingir of which the figure is a longitudinal sectional view of ahydraulic press with a bag of lampblack therein.

In utilizing the apparatus, I take a mass of lampblack 1() in the usualform of a loose powder, and preferably enclosed in an envelope, such asa paper bag. 11, and place the same in the compression chamber.' 12 of ahydraulic press 13. the press is then bolted down and a hydraulicpressure of about three thousand 'pounds is kept on the ram 15 for aboutone minute. The pressure is then released, the head is opened, and thecompactly pressed lampblack is removed from the press in the form of asolid cake.

It is essential that the compression chamber be vented so that the airWithin the chamber and within the mass of lampblack can escape duringthe pressing operation,

.and for this purpose I provide a plurality of vent openings 16,preferably disposed in the head 14 of the press. The envelope 11 Thehead 14 oi':l

plained in this manner. Lampblack, in thc form of a loose powder,exhibits particles isolated from each other by air in vwhich conditionit is easily dispersed. Upon'high pressure being;r applied, this air issqueezed from between the particles and the contiguous moleculescompressed into close union which they retain, after removal of thepressure, by virture of their own molecular cohesion.

It is found that when lampblack, iu cake form in which the particles arebound together by their own molecular cohesion, is compounded withrubber, there is no dispersion of the lampblack throughout theatmosphere, for as soon as the cake is broken into lumps, the lumps areimbedded by the mill rolls in the rubberbatch, which latersurrounds thesmaller particles and powder into which the lumps are subsequentlyreduced, and positively prevents the escape of the lampblack.

lVhile the invention is especially applicable to the treatment of lampblack it is obvious that it could be advantageously' extended to thetreatment of other finely divided carbon such as carbon Ablack and thelike.

Having thus described my invention, what I claim and desire to protectby Letters Patent is:

1. A process for transforming finely divided carbon from a light,fluffy, powder condition to a solid block which comprises, subjectingthe carbon as such being treated upon all sides to a high pressure,while simultaneously venting the mass to permit the pressure to forcethe air therefrom through the vent until cohesion is produced betweenthe particles and a permanent block 'foi-med.

2. A process for transforming finely divided carbon from a, light,fluffy, powder the pressure to force the air therefrom through the ventuntil cohesionis `produced 10 between the particles and a permanentblock formed.

Signed at Detroit, Mich., this 27th day of October 1916.

WILLIAM VVMCMAHAN.

